To short answer, I provide already detail explanation links Hope it help you !.
I consider you understand Following terms
- Please follow it firstly official documentation for overall idea how it works
2 Create a storefront and Configure the server to load your storefront
if you need to create multiple store(e.g Nike) , store view(US|IN|FR)
- Setup multi-Website switcher :
if you need to change store view US|UK|France|German| drop down from
- Setup multi-Website :
if you need to setup multi-store for different domain (e.g domain1.com,domain2.com) manage from single admin.